It is known that sufficient lubrication is necessary for good eye health. Tears nourish the ocular tissues and protect the surface of the eye from foreign bodies. Changes in the ocular surface due to alterations in the quality or quantity of tears (caused by either decreased tear production or increased tear film evaporation) can lead to dry eye syndrome and other inflammatory ocular conditions. Typical symptoms of dry eye and other inflammatory ocular conditions include dryness, burning, itchiness, scratchiness, stinging, a sandy/gritty sensation, tired eyes, and sensitivity to light. These symptoms typically worsen as the day progresses. Other symptoms include pain, redness, a pulling sensation, pressure behind the eye, and a feeling that there is something in the eye. Because of the range of symptoms, individuals suffering from dry eye and other inflammatory ocular conditions often complain of eye irritation and discomfort.
If dry eye and other inflammatory ocular conditions are left untreated, it can produce complications that can cause eye damage, resulting in impaired vision or (rarely) the loss of vision. When symptoms are severe, they can interfere with the quality of life of an individual suffering from dry eye.
The ocular surface is normally covered by a tear film—the clear liquid that coats the outer tissues of the eye. The tear film is composed of three layers; the most superficial layer of the tear film is the lipid layer, which covers the aqueous layer of the tear film, and then the third layer is a mucinous layer. Any abnormality in any one of the three layers, particularly a disturbance in the lipid layer, produces an unstable tear film, which results in symptoms of dry eye and other inflammatory ocular conditions.
Current methods of alleviating the symptoms of dry eye include administering artificial tears to the ocular surface. These artificial tears, however, must be administered every few hours, and only provide temporary and incomplete relief of the symptoms of dry eye. Thus, there is a need for compositions and methods to treat various eye disorders and conditions, including but not limited to, dry eye syndrome and other inflammatory ocular conditions.
It has been noted that consumption of dark fleshed fish containing dietary omega-three fatty acids is associated with a decreased incidence of dry eye symptoms. Omega-three and omega-six fatty acids are compounds known as “essential” fatty acids because they are essential to human health. These fatty acids, however, are not produced by the human body; instead, the fatty acids can be introduced into the body via dietary intake, either in the form of food or as supplements. Oral consumption of omega-three fatty acids, however, does produce potential side effects such as effects on bleeding time, increasing cholesterol (LDL) level, high caloric intake, a fishy aftertaste, and gastrointestinal disturbances. Because of their potential to improve the symptoms of dry eye and other inflammatory ocular conditions, work on omega-three fatty acids when used in a topical application to the ocular surface has shown promising results. (Rashid, S. et al., “Topical Omega-3 and Omega-6 Fatty Acids for Treatment of Dry Eye,” Arch Opthalmol. 2008; 126(2):219-225). Using topical formulations of fatty acids to treat dry eye would provide more flexibility for treatment, including lessening side-effects that patients can experience from oral intake of fatty acids.
Omega-three fatty acid—containing oils such as botanical oils have been used to form non-irritating ophthalmic compositions (e.g., U.S. Patent Application Pub. 2010/0305045 (Abbott Medical Optics, Inc.)). Hydrogel contact lenses can comprise a polymeric matrix and a hydrophobic comfort agent distributed in the polymeric matrix, where the hydrophobic comfort agent can include a monoglyceride, a diglyceride, a triglyceride, a glycolipid, a glyceroglycolipid, a sphingolipid, a sphingoglycolipid, a phospholipid, a fatty acid, a fatty alcohol, a hydrocarbon having a C12-C28 chain in length, a mineral oil, a silicone oil, or a mixture thereof. (U.S. Patent Application Pub. 2010/0140114 (Ciba Vision Corporation)). Ophthalmic lenses have been provided with anti-toxin agents that are monoesters and/or diesters of a polyhydric aliphatic alcohol and a fatty acid containing from eight to eighteen carbon atoms and wherein said monoester has at least one hydroxyl group associated with its aliphatic alcohol residue (U.S. Pat. No. 5,472,703). Resolvins and protectins have been used to help treat pathologies associated with angiogenesis and ocular neovascularization, particularly associated with retinopathy of prematurity (e.g., U.S. Patent Application Pub. 20100105773 (Children's Medical Center Corp.)). Lipoxins have also been used to treat pathologies associated with ocular neovascularization (e.g., U.S. Patent Application Pub. 20100105772 (Serhan, et. al.)).
Accordingly, there remains a need in the art for improved ocular products that relieve/mediate symptoms of dry eye and other inflammatory ocular conditions.